- Add install.ps1 mirrored from install.sh patterns
- Same env var overrides (BSK_REPO, BSK_VERSION, BSK_INSTALL_DIR)
- Default install dir ~/.local/bin
- Fetches latest version from version.json via Invoke-RestMethod
- Downloads, extracts zip, installs bsk.exe
- Adds to user PATH persistently with idempotent check
- Supports x64 and ARM64 architecture detection
- Update README.md Windows section with irm | iex one-liner
- Update AGENT_INSTALL.md with Windows PowerShell instructions
